Method and apparatus for generating steam for a cooking device

ABSTRACT

A method and steam generator includes a steam generator container having a heated wall surface, an inlet for a liquid and an outlet for removing the vaporized liquid or steam, a rotor, which is mounted for rotation in the container and causes a rotational flow of the liquid outwardly against the heated wall to cause vaporization. During rotation of the rotor, outer edges of the blades of the rotor contact the wall surface to either abrade or wipe deposits, such as lime, from the wall surface.

BACKGROUND OF THE INVENTION

The invention is directed to a method for generating steam, particularlyfor a cooking device, whereby a liquid within a steam generating vesselis caused to boil by a method of heating at least one heatable wallsurface of the steam generating vessel, placing the liquid into rotationwhile being heated and pressing the liquid against the heatable wallsurface due to centrifugal forces due to the rotation, allowing thesteam arising due to a vaporization of at least a part of the liquid toescape from the steam generating vessel through a steam outlet andseparating drops of the liquid entrained with the steam from the steam.The invention is also directed to an apparatus for generating steam,particularly for a cooking device, which apparatus comprises a steamgenerating vessel that can be at least partially filled with a liquidvia an admission or inlet and from which steam can proceed to a steamoutlet, and has a heating device for heating the liquid in the steamgenerating vessel for the purpose of generating steam.

Traditional steam generators as particularly employed in cooking devicesusually comprise a boiler that is partially filled with water that isbrought to a boil with heating elements. The space requirement of such asteam generator is mainly defined by two factors, which are the volumepart that is filled with liquid water and the volume part of the gasspace located above the water.

The first volume part is thereby limited by the size of the heatingelements and the space required between the heating elements for theflooding thereof and for carrying off the steam bubbles. The size of theheating elements for a prescribed heating capacity is in turn defined bythe Leidenfrost effect, in accord wherewith a specific surface powerdensity of a heating element dare not be exceeded when heating avaporizable liquid since a closed intermediate steam layer that impedesthe heat emission otherwise forms between the surface of the heatingelement and the liquid. The Leidenfrost effect is nicely demonstrated inthe phenomenon that drops of water do not immediately vaporize on ared-hot plate but first move in a quasi dancing motion since, carried bya steam layer that is formed, they move irregularly on the plate.

The second volume part is required in order to separate the steam fromentrained drops of water. The size and design of the second volume part,i.e. of the gas space above the liquid, are critical for the quality ofthe steam. The steam quality is particularly determined by the size ofthe water surface that the stream of steam must pass. The emergingsteam, namely, entrains all the more water the larger the stream ofsteam is per water surface.

Given traditional steam generators, thus, a high space requirementsderives overall from the above considerations when a high steam qualityis to be produced. Additionally, however, it must also be pointed outthat the time required to make a known, water-filled steam generatoroperational is also dependent on the amount of water filled in that isrequired for reliably covering the heating elements, and this, in turn,makes demands of the size of the steam generator.

Steam generators wherein a rotational flow is induced in asteam-generating liquid by injecting a further liquid are known in thefield of power plants, particularly nuclear power plants. Thecentrifugal forces accompanying the rotational flow are thereby used forthe precipitation of contaminants, as disclosed by U.S. Pat No.4,972,804 or, respectively, DE 690 13 906 T2.

Steam generators are also known wherein the entire tubular orbarrel-shaped steam generator vessel is placed into rotation. Thisinvolves high energy and cost outlays and requires a great structuralcomplexity that makes a rotating bearing of the steam generating vesselnecessary, whereby an admission or, respectively, discharge of liquid isnecessarily only practical via the axis of rotation. DE 2 214 566, forexample, discloses such a rotating steam generator that is designed forthe vaporization of organic drive fluids in a closed circulation of aRankine motor. The steam generator disclosed by German Letters Patent904 653 works similarly and this, however, additionally comprises aregulation for the supply of liquid for the purpose of creating a liquidring having a specific thickness.

DE 27 57 913 A1 discloses a rotating steam generator with a rotatablyseated boiler that structurally foregoes rotatable lead-throughs for theintroduction or, respectively, removal of a liquid work medium.

DE 37 83 361 T2 discloses a tandem separator for a steam/water mixture,whereby helically coiled baffles place the steam/water mixture intorotation.

DE 692 07 830 T2 discloses a steam generator arrangement for ovenswherein thin water jets or, respectively, small drops of water, whichare placed into rotation, descend onto a heating device in order to bevaporized.

The known steam generators, however, do not work satisfactorily for thevaporization of tap water but exhibit the serious disadvantage that thedissolved minerals which are contained in the tap water, particularlylime, will deposit at the walls and built-in parts of the steamgenerator. This can lead to the outage of or damage to the steamgenerator, which can usually only be prevented by a regular chemicaldecalcification. The post-operation maintenance jobs that becomenecessary as a result thereof are in turn cost-intensive.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to develop a methodof the species as well as the apparatus of the species for generatingsteam such that the disadvantages of the Prior Art are overcome in that,in particular, small steam generators for outputting high-quality steamcan be offered that are also quickly operational, cost-beneficial,flexibly heatable and dependable without tending toward defervescencesand without requiring a regular decalcification.

The object of the invention is achieved in that the liquid is placedinto rotation by at least one first rotor that is rotatably seated inthe steam generating vessel.

It is thereby inventively proposed that the centrifugal forces of theliquid and/or of the steam are higher than the gravitational forces ofthe liquid and/or of the steam.

It can also be provided in the region wherein the drops of liquid areseparated that the liquid and the steam are at least partially forcedagainst at least one diaphragm, so that potential eddies are at leastpartially generated in the liquid and/or the steam and/or no heating ofthe heatable wall of the vessel occurs.

It is inventively proposed that contaminants of the liquid areeliminated in that the liquid is forced against at least one diaphragm.

It is also proposed that the liquid is supplied into the vessel with aminimum velocity, preferably directed onto the heatable wall surfaceand/or onto the first rotor.

Alternatively, it is proposed that the filling level of the vessel isidentified, preferably from outside the vessel, by measuring acentrifugal force-induced pressure against at least one wall surface ofthe vessel.

An inventive method is characterized in that liquid condensed and/orvaporized in the steam escaping from the steam generating vessel isplaced into rotation by a second rotor in at least one further oradditional liquid separation vessel following the steam generatingvessel, and any condensate is separated and discharged from the liquidseparation vessel, and is preferably resupplied to the steam generatingvessel.

It can thereby be provided that the first rotor in the steam generatingvessel and the second rotor in the liquid separation vessel are placedin rotation via a motor, preferably via the rotational axis.

It is also provided that the steam is at least partially supplied to thesteam outlet through a pipe arranged in the steam generating vessel,preferably in the form of a hollow shaft in communication with the rotoror, respectively, rotors.

It can be preferably provided that at least one of the first and thesecond rotor comprises an at least regionally abradant contact with thewall surface or deposits on the wall surface of the steam generatingvessel or, respectively, liquid separation vessel at least during therotation, and at least partially strips the deposits, particularly inthe form of lime incrustations, from the wall surface.

It can thereby be provided that the distance between the first and/orsecond rotor and the appertaining wall surface is dimensioned so slightthat a deposit being formed, particularly a lime incrustation, is erodedupon rotation of the first or, respectively, second rotor.

It is also proposed that the first and/or second rotor comprises or,respectively, comprise no contact with the corresponding wall surface inthe idle condition and is pressed at least regionally in the directionof the corresponding wall surface due to centrifugal forces uponrotation.

It is also proposed that the wall surface and/or the rotor is or,respectively, are dry-heated after an operating phase and/or a wettingwith liquid given rotating and/or idle rotor, whereby an adhesion of therotor to the wall surface due to deposits is prevented.

It is also inventively proposed that the steam generating vesselempties, preferably automatically, in the idle condition of the firstrotor, particularly via a vapor-tight waste water drain.

It can preferably be provided that the admission or inlet is made of aflexible material and is deformed by the pressure of the incoming fluidin order to at least partially strip deposits from the inlet.

Among other things, it is inventively proposed that the admission iscooled by a liquid stream that is continuously maintained via a controland/or regulating device, whereby the liquid is taken from a reservoirand/or from a feed conduit, and deposits are at least regionallyprevented.

The invention is also directed to an apparatus for generating steam thatis characterized by a first rotor in the steam generating vessel viawhich at least the liquid can be placed into rotation.

It is thereby provided that the vessel comprises two ends lying oppositeone another, whereby the inlet and the steam outlet are either botharranged at one end or each is arranged at a different end.

It is also proposed that the steam generating vessel is rotationallysymmetrical around an axis, preferably essentially tubularly, or isconically expanded from the inlet to the steam outlet.

An inventive apparatus can also be characterized in that the axis of thesteam generating container coincides with the rotational axis of thefirst rotor, whereby the rotational axis preferably proceeds essentiallyparallel to the direction of the gravitational force.

It is also proposed that the heating device works with electricalheating coils, a gas burner, a heat exchanger, electrical induction,thermal radiation, direct or indirect flame charging, thick-film heatingor an electrically conductive ceramic as material of the heatable wallsurface of the steam generating vessel, whereby the outer surface of thesteam generating vessel is enlarged, preferably by ribs, embossingand/or coils and/or the flow velocity of the combustion gas isincreased.

The inventive apparatus is also characterized by at least one diaphragmfor the elimination of drops of liquid entrained by the steam and/orcontaminants in the liquid.

It is thereby also proposed that a first diaphragm is arrangeddownstream of the inlet and/or a second diaphragm is arranged upstreamof the outlet.

An inventive apparatus can also be characterized by an opening for apreferably automatic emptying of the liquid given standstill of therotor and/or by a third diaphragm in the region of the steam generatingvessel with the least gravitation potential, whereby the opening isclosed during rotation by a closure mechanism that preferably comprisesa siphon trap.

It is also proposed that the first rotor can be driven by a motor via ashaft, whereby the shaft is, in particular, a hollow shaft with radialbores and/or slots that are arranged along the long side of the hollowshaft in order to enable a steam transfer from the steam generatingvessel to the steam outlet.

Further, an inventive apparatus can be characterized by a liquidseparation vessel between the steam generating vessel and the steamoutlet, whereby a liquid return preferably proceeds from the liquidseparation vessel to the steam generating vessel.

It can thereby be provided that a second rotor is rotatable in theliquid separation vessel, and is preferably mechanically coupled to thefirst rotor.

It can also be inventively provided that the first and/or the secondrotor comprises a stripper device that strips deposits from at leastregions of a wall surface of the steam generator vessel or,respectively, liquid separation vessel during rotation.

It can thereby be provided that the stripper device comprises brushes,lamellae, fringes and/or lips, which are preferably composed offoodstuff-fast, heat resistant material.

It is also proposed that the stripper device comprises a materialreinforcement at least regionally at its side lying closest to the wallsurface during rotation.

It is preferably inventively proposed that the stripper device comprisesno contact with the wall surfaces in its idle condition but does uponrotation, preferably via employment of at least one spring system.

It can also be provided that the first and/or second rotor is or,respectively, are fashioned spirally, helically and/or star-shaped inthe form of a paddle, which preferably has two paddle halves.

Finally, it is proposed that the rotor itself is implemented flexible,preferably in the form of brushes, lamellae, fringes and/or lips andexhibits no contact with the wall in its idle condition.

In that the invention is the first to have undertaken the step ofrotating the built-in parts of the steam generating vessel instead ofthe steam generating vessel itself, the following advantages have, inparticular, been achieved:

-   -   i) recusation of the mass moment of inertia, as a result whereof        the energy requirement is reduced at the same time, response        times are shortened, control times are shortened, bearing forces        are reduced and balancing problems are reduced; and    -   ii) simplification of the structure, for example by simplifying        the installation and contacting of a heating device, as well as        avoiding structurally complicated structures of a type that are        standard given rotating outside vessels in order, among other        things, to avoid rotatably implemented leads.

Overall, thus, the manufacturing and maintenance costs are reduced givena simultaneous enhancement of the use time.

Developments according to the invention are also based on the surprisingperception that involved and cost-intensive maintenance work fordecalcification at the steam generators becomes superfluous and that amaximum heat transfer from the walls to the liquid remains is assuredduring operation because the inside, rotating units function, so tospeak, as a stripper device with which the deposits at the walls areinstantaneously abraded during operation, i.e. during rotation.

Further features and advantages of the invention derive from thefollowing description wherein three exemplary embodiments of theinventive apparatus are explained in detail on the basis of schematicdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view through a first embodiment with rotorat rest;

FIG. 2 is a cross-sectional view through a second embodiment with rotorat rest; and

FIG. 3 is a cross-sectional view through a third embodiment with rotorat rest.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As can be derived from FIG. 1, an inventive steam generator 1 acomprises a steam generating vessel in the form of a tubular boiler 2with an admission or inlet in the form of a water inlet 3 and a steamoutlet 4 at the upper end of the boiler 2, a diaphragm 5, whichdiaphragm separates the boiler 2 from the steam outlet 4, for condensateand contaminant separation, heating elements 6 in the form of athick-film heater surrounding the tubular boiler 2, and a rotor in theform of a paddle 8 rotatable around a rotational axis 7 that coincideswith the longitudinal axis of the boiler 2. The paddle 8 is seated withtwo bearings 9 and is driven with a motor 11 via a clutch 14, which isintended to compensate for adjustment errors, and a shaft 13. The paddle8 comprises two paddle halves 8 a, which have respective long paddlesides or edges 8 b neighboring the wall surface 12 of the boiler 2, arecess 15 in the region of the diaphragm 5 and an impact disk 16 inorder to generate a potential eddy in front of the diaphragm 5. A wastewater drain 17 is located at the lower end of the boiler 2, and it has acollar 18 in order to avoid water losses due to flowing in a boundarylayer. The waste water drain 17 is closed only with a siphon trap 19 inorder to avoid steam losses, so that the boiler 2 automatically emptiesgiven standstill of the paddle 8.

With the steam generator 1 a described with reference to FIG. 1, wateris supplied to the boiler 2 via the water inlet 3 and is placed inrotation by the paddle 8, which is rotating around the rotational axis 7in order to force the water against the wall surface 12 of the boiler 2,which is heated via the heating elements 6, and leads to a fast anduniform heating of the water. At the same time, the paddle halves 8 athat are held in their idle position shown in FIG. 1 by springs (notshown) and at whose long sides 8 b fine, flexible lips (not shown) arelocated are pressed against the wall surface 12 of the boiler 2 due tothe rotation. The pressing power is thereby dimensioned such that thelips wipe the wall surface 12 only lightly. Salt deposits, particularlylime incrustations, are thereby avoided. In addition, the long sides 8 bcan comprise reinforcements in order to achieve an optimallylong-lasting stripping effect given low wear or with a flexible designof the rotor of the stripper device, the ends of the elastic lips of thesides 8 b can be reinforced in order to increase the pressing poweragainst the wall surface 12 during the rotation. Via the diaphragm 5,moreover, both contaminants of the water as well as drops of waterentrained with the generated steam, which are forced against the wallsurface 12 of the tubular boiler 2 due to the rotation of the paddle 8,are prevented from emerging from the steam outlet 4 together with thesteam.

The geometry at the diaphragm passage or opening can be designed forenhancing the separation rate of the steam and the liquid so that apotential eddy that can be reinforced by the preceding impact disk 16 isinduced.

Despite the counter-measures, an entrainment of drops of water due tohigh flow velocities can nonetheless occur given a small diameter of theboiler 2. In the embodiment of the inventive steam generator 1 bdescribed in FIG. 2, the boiler 2 is therefore followed by a waterseparation chamber 20 that again separates entrained water from thesteam and that is limited by a second diaphragm 21 with an opening. Asecond paddle 22 rotates in this water separation chamber 20, whichpaddle 22 is driven by the same shaft 13 as the paddle 8 and likewisehas a recess 23 and an impact disk 24 in order to generate a potentialeddy. The drops of water separated from the steam due to the rotationgenerated by the paddle 22 are returned into the boiler 2 via a waterreturn 25 in the form of a tube or hose conduit. All other components ofthe inventive steam generator 1 b according to FIG. 2 correspond to theinventive steam generator 1 a according to FIG. 1.

FIG. 3 shows another inventive steam generator 1 c wherein additionalmeasures are implemented in order to reduce the water entrainment givena small boiler diameter, and identical components of this generator areprovided with identical reference characters. Here, the paddle 8 isdriven by a hollow shaft 26 that simultaneously serves the purpose ofconducting the generated steam out of the boiler 2. In order to move thesteam into the inside of the hollow shaft 26, the latter must beprovided with radial bores or slots 29 a over its entire moistenedlength in the vaporizer space, i.e. the boiler 2. The diameters ordensity of the bores or slots 29 a are varied in axial direction so thatthe flow-conditioned pressure drop in the hollow shaft 26 is compensatedand, thus, the flow component in the direction of the rotational axis 7in the boiler 2 outside the hollow shaft 26 is minimized, as is theentrainment of water at the same time. Outside the boiler 2, the steamcan in turn be coupled out, for example, through further radial bores 29b in the hollow shaft 26 or through an axial opening (not shown) at theend of the shaft 26.

The shaft 26 is seated at the lower end of the boiler 2, whereby it cantaper into a correspondingly thinner, solid shaft. At the upper end ofthe boiler 2, the hollow shaft 26 is conducted out of the boiler 2through a seal or a vapor-tight bearing 27 into a steam dischargechamber 28 lying thereabove. In this steam discharge chamber 28 abovethe boiler 2, the hollow shaft 26 has the bores 29 b in order to allowthe generated steam to emerge in turn and be supplied to the steamoutlet 4. The hollow shaft 26 is in turn conducted out at the other endof the steam discharge chamber 28 with a seal or vapor-tight bearing27′, and the hollow shaft 26 can merge into a thinner, solid shaft in orabove the steam discharge chamber 28. Above the steam discharge chamber28, the hollow shaft 26 is coupled to the motor 11 via a clutch 14 forcompensating alignment errors between the motor shaft and the hollowshaft 26.

Additionally, the filling level of the steam generator 1 a, 1 b or 1 ccan be acquired by measuring a centrifugal force-induced pressure at theoutside walls of the boiler 2.

A decalcification of an inventive steam generator 1 a, 1 b or 1 c iseffected by the flexible lips at the long paddle sides 8 b of the paddlehalves 8 a that continuously erode the deposits from the outside wallduring operation. The lips themselves do not thereby wear significantlysince they themselves calcify in the region of immersion into the waterfilm and it is thus mainly lime scraping against lime. However, anexcessive amount of lime can also not collect at the paddle 8 since thisis driven outward by the centrifugal force and is ultimately scraped offthereat. The lime meal that occurs must merely be removed from theboiler by being regularly rinsed or, respectively, by changing thewater. The employment of flexible lips as stripper device or theflexible design of the rotor in and of itself yields the advantage thatno adhesion of the rotor to the wall surface 12 can occur in the idlecondition due to potentially existing deposits since the centrifugalforce upon rotation produces the contact of the rotor or the stripperdevice with the wall surface 12. In order to enable an automaticemptying, the lower end of the boiler 2 can be provided with anadditional diaphragm or a closure mechanism (not shown). The diaphragm 5can thereby be combined with just such a diaphragm upstream of the steamoutlet 4.

Both individually as well as in arbitrary combination, the features ofthe invention disclosed in the above specification, in the claims aswell as in the drawings can be critical for realizing the variousembodiments of the invention.

1. A method for generating steam comprising the steps of providing asteam generating vessel having an outer wall, a liquid inlet and anoutlet, at least a first rotor mounted for rotation in the steam vessel,and a drive for rotating the rotor, heating the wall surface of thesteam-generating vessel, adding liquid through the inlet, rotating therotor to place the liquid in rotation and to press it against the heatedwall surface, separating any entrapped drops in the steam before itexits the outlet and removing deposits on the wall surface of thesteam-generating vessel by an outer edge of the rotor lightly engagingsaid wall surface.
 2. A method according to claim 1, wherein the step ofrotating the rotor creates centrifugal forces on the liquid and anysteam, which centrifugal forces are higher than the gravitational forcesof the liquid and steam.
 3. A method according to claim 1, wherein thestep of separating includes at least partially forcing the liquid andsteam against at least one diaphragm to create potential eddies in theliquid and steam and against non-heated wall portions of the vessel. 4.A method according to claim 3, wherein the step of at least partiallyforcing the steam and liquid against a diaphragm eliminates contaminantsof the liquid.
 5. A method according to claim 1, wherein the step ofadding liquid into the vessel adds the liquid as a stream with a minimumvelocity directed onto one of the heated wall surface and first rotor.6. A method according to claim 1, which includes determining the fillinglevel of the vessel by measuring the centrifugal force-induced pressureagainst at least one wall surface of the vessel.
 7. A method accordingto claim 1, wherein the step of providing the steam generator provides asteam generator with a liquid-separation vessel with a second rotorlocated downstream from the first rotor, said second rotor being mountedon the drive shaft for the first rotor and includes placing the steamand liquid escaping the steam-generating vessel into rotation by thesecond rotor to further separate liquid from the steam and thendischarging the steam free of liquid from the vessel.
 8. A methodaccording to claim 7, wherein the first rotor and the second rotor areplaced in rotation via the same drive arrangement.
 9. A method accordingto claim 7, wherein the second rotor includes a regionally abradantcontact with the surface of the liquid separation vessel at least duringits rotation and at least partially strips the deposits from the wallsurface.
 10. A method according to claim 7, wherein the distance betweenthe second rotor and the wall surface is dimensioned so slight that thedeposits being formed are eroded by rotation of the second rotor.
 11. Amethod according to claim 7, wherein the first and second rotors have nocontact with the corresponding wall surface while in an idle conditionand are pressed radially outward into contact with the wall surface bycentrifugal force caused by said rotation.
 12. A method according toclaim 1, wherein the steam generator includes a hollow shaft incommunication with the rotor and with the steam outlet and the methodincludes drawing steam into said hollow shaft and discharging it at thesteam outlet free of droplets of liquid.
 13. A method according to claim1, which includes preventing adhesion of the rotor to the wall surfacesdue to deposits by dry-heating at least the wall surfaces after anoperating phase or a wetting of the walls with a liquid.
 14. A methodaccording to claim 1, wherein stopping rotation of the rotorautomatically empties the steam-generating vessel via a vapor-tightwaste water drain.
 15. A method according to claim 1, which includesproviding an inlet made of a flexible material, which is deformable, sothat the pressure of incoming fluid through the inlet at least partiallystrips deposits from said inlet.
 16. A method according to claim 1,which includes regulating and controlling a fluid stream entering theinlet to cool the inlet and to prevent deposits thereon.
 17. Anapparatus for generating steam, said apparatus comprising asteam-generating vessel having an inlet for receiving a liquid and anoutlet through which steam can escape, a heating device for heatingliquid in the steam-generating vessel, at least one first rotor beingmounted in the steam-generating vessel, an arrangement for rotating saidrotor so that liquid in the steam-generating vessel is placed intorotation and forced against a wall surface of the steam-generatingvessel, said first rotor including a stripper device that at leastregionally strips deposits from a wall surface of the steam-generatingvessel during rotation thereof.
 18. An apparatus according to claim 17,wherein the vessel includes two ends lying opposite one another and theinlet and outlet are disposed in at least one of said ends.
 19. Anapparatus according to claim 18, wherein the steam-generating vessel hasa rotationally symmetric wall surface extending between said ends. 20.An apparatus according to claim 19, wherein an axis of thesteam-generating vessel coincides with the rotational axis of saidrotor, so that the rotational axis preferably proceeds essentiallyparallel to the direction of gravitational force.
 21. An apparatusaccording to claim 17, wherein the heating device is selected from agroup consisting of electrical heating coils, gas burners, heatexchangers, electrical induction, thermal radiation, direct flamecharging, indirect flame charging, thick-film heating, and anelectrically conductive ceramic material as a heatable wall surface forthe steam-generating vessel and an outer surface of the steam-generatingvessel being enlarged by elements selected from ribs, embossments andcoils.
 22. An apparatus according to claim 17, which includes at leastone diaphragm for elimination of drops of liquid entrained by the steam.23. An apparatus according to claim 22, wherein the at least onediaphragm is arranged downstream of the inlet and a second diaphragm isarranged between the first-mentioned diaphragm and the outlet.
 24. Anapparatus according to claim 17, which includes an opening forautomatically emptying the liquid from the steam-generating vesselduring standstill of the rotor, said opening being closed duringrotation by a closing mechanism including a siphon trap.
 25. Anapparatus according to claim 17, wherein the rotor is driven by a motorvia a shaft, said shaft being a hollow shaft with radial openingsarranged along the length of the shaft in order to enable steam transferfrom a steam-generating vessel to the steam outlet.
 26. An apparatusaccording to claim 17, which includes a liquid separation vessel betweenthe steam-generating vessel and the steam outlet, a liquid returnproceeding from the liquid separation vessel back to thesteam-generating vessel.
 27. An apparatus according to claim 26, whereina second rotor is rotated in the liquid separation vessel and is coupledfor rotation with the first-mentioned rotor.
 28. An apparatus accordingto claim 27, wherein the second rotor includes a stripper device thatstrips deposits from at least regions of the wall of the separationvessel during rotation.
 29. An apparatus according to claim 17, whereinthe stripper device is selected from a group consisting of brushes,lamellae, fringes and lips.
 30. An apparatus according to claim 17,wherein the stripper device comprises a material reinforcement at leastregionally on a side lying closest to the wall surface during rotation.31. An apparatus according to claim 17, wherein the stripper device hasno contact with the wall surface during an idle condition of the rotor,but upon rotation of the rotor, moves into engagement with the wallsurface.
 32. An apparatus according to claim 17, wherein the rotor isfashioned from a group consisting of spiral rotors, helical rotors,star-shaped rotors having paddles preferably with two paddle halves. 33.An apparatus according to claim 17, wherein the rotor is formed of aflexible material selected from brushes, lamellae, fringes and lips andhas no contact with the wall while in an idle condition.